Electron discharge device



J 1946- s. H. DODINGTON ELECTRON DISCHARGE DEVICE Filed Dec. 24, 1941INVENTOR. VE/V/i JQD/IVGTOA/ 'AITQRNEK Patented June 25, 1946 ELECT-RONDISCHARGE DEVICE Sven H. Dodington, Forest Hills, N. Y., assignor toFederal Telephone and Radio a corporation of Delaware Corporation,

Application Decembcr 24, 1941, Serial No. 424,245

11 Claims. (Cl. 250-27.'5)

This invention relates to .highfrequency electron discharge devices, andmore .particularlytc suchdevices of the kind which are mounted betweentwo lengths of concentric transmission line.

.An object of the invention is the, provision of a .high irequencymulti-grid electron discharge device which, while simple in constructionand stable in operation, results in a substantial gain per stage over aconsiderable bandwidth.

Further objects of the invention are the reductionor substantialelimination of lead inductan'ce insofar as the high frequency circuitsare concerned, and the substantially complete isolation of plate andgrid circuits without resort to external bypass condensers.

According to the invention, an annular cathode is provided which issecured to or integral with an annular mounting vdisc, the periphery ofwhich is sealed between two portions 01 the glass envelope and projectsbeyond its outer wall. The projecting edge of the mounting disc issecured between the abutting ends of the outer tubular conductors oftwojs'ect'ions of concentric transmission line which respectively formpart of the grid and plate circuits. The plate electrode is mounted upona copper sleeve which is connected by a seal to a reentrant portion ofthe glass envelope, through which sleeve the central conductcr of theplate section of transmission line extends to make direct contact withthe plate electrode. In the embodiment described the device isconstruc'ted'as apentode, the control grid being connected to the innerconductor of the grid section of transmission line and the screengrid tothe cathode mounting disc over a bypass condenser located inside .theenvelope. The suppressor grid is connected directly to the cathodemounting disc inside the envelope,

In the drawing which accompanies and forms part of this specification:

(Fig. 1 is a longitudinal cross-section of a device constructedaccordingto the invention; and

'2' is apartial, enlarged cross-sectional view of a detail ofconstruction.

The cathode C consists of an annular channelled ring which is integralwith or bonded to al'arge disc D, for example oi copper, fused betweentwo sections of the glass envelope '3. The periphery of the discDextends beyond the glass envelope B and is welded .or otherwise securedbetween flanges F-on the outer tubes T, T1 of the concentric linesections. "The disc 11) thus constitutes the earth return of theconcentric line sections and is therefore a part of both grid and platecircuits, but its reactance even at relatively high frequencies will notbe excessive. The cathode heater H is located in the channel at the rearof the cathode, one end being connected to the disc D and the other endto a supply lead F which is brought out through the glass envelope B andthe tube T as close to the disc D as possible.

The plate electrode P, which comprises a thick disc locatedin a planeparallel to that of the cathode disc D, is welded to a copper tube orsleeve J which is joined to a reentrant portion of the glass envelope Bthrough a copper-to-glass seal. The end central conductor L2 of theplate circuit transmission line section extends into the tube J and isin direct contact with the plate P.

Between the cathode C and plate P there are mounted in any suitablemanner and in parallel planes transverse to the axis of the structure, acontrol grid CG, a screen grid SG and a suppressor grid SP. A lead =GLfor the control grid CG extends through the central aperture in thecathode and is brought out through the envelope and is connected to thecentral conductor L1 of the grid circuit transmission line section/As ismore clearly shown in conj un-ction with Fig. 2, the screen grid SG isconnected to an annular plate or ring R which is separated from theoathode disc Dby a layer-or dielectric I so as to constitute a bypasscondenser BP :for the screen grid. The supply lead S forthe screen gridpasses through the outer tube T1 of the plate transmission line sectionas close to the cathode disc D as possible. The suppressor grid SP istied directly to the cathode disc D atone or more points inside theenvelope. As the majority of the plate capacity is to the suppressorgrid, this ensures that the circulating alternating plate current willflow through a minimum impedance common to the grid and plate circuits.

Although one embodiment of the invention has been shown and describedfor the purpose of illustration, it will be understood thatmodifications and alterations occurring to those skilled in the art maybemade without departing from the scope of the invention as defined inthe appended claims.

What I claim is: g

1. An electron discharge device for the amplification of high frequencywaves comprising a first section of concentric transmission line, asecond section of concentric transmission line, a glass envelope, anannular cathode connected to an annular disc which is sealed between twoportions ofrsaid glass envelope and projects beyond the outer wall ofsaid envelope, an anode, a control grid, a screen grid and a suppressorgrid grid and anode electrodes being disposed within said envelope,means securing the projecting edge of said annular disc between abuttingends of the outer tubular conductors of the first and second sections oftransmission line, a galvanic connection inside the envelope from saidsuppressor grid,

to said annular disc, a conductor leadextending from said control gridthrough one end of said envelope to the central conductor of said firstsection of transmission line, and a direct con;-

nection between said anode and the end of the central conductor of saidsecond section of transmission line.

2. An electron discharge device according to,

claim 1 wherein a by-pass condenser for said screen grid is providedwithin said glassenvelope. 3. An electron discharge device comprising 'aglass envelope, an annular metallic disk, an an nular cathode connectedto said disk which is sealed between two portions of said glassenvelope, an anode disposed in a plane parallel to the plane of-saidcathode, first and second grid electrodes disposed between said cathodeand said anode, said cathode, grid and" anode electrodes being disposedwithin said envelope, a metallic plate inside said envelope adjacentsaid metallic disk and separated from it bya layer of dielectric, and aconductive connectionextending from said second grid; electrode to saidmetallic plate. a 4

4. An electron discharge device comprising a glass envelope, an annularmetallic disk, an annular cathode connectedto said-disk which is sealedbetween two portions'of saidglass envelope, an anode disposed ina planeparallel to the plane of said cathode, three grid'electrodes disposedbetweensaid cathode and said anode in planes parallel to'the plane ofsaid cathode, said cathode, grid and anode electrodes being disposedwithin said envelope, and a direct conductive connection within saidglass envelopeextending between said annular metallic disk and the gridelectrode-nearest the anode.

5. An electron discharge device comprising'a glass envelope, an annularmetallic disk, an annular cathode connected to said'disk which is Isealed between twoportions of said glass envelope and projects beyondtheouter wall of said envelope, an anode disposed in a. plane parallelto the plane of said cathoda. a grid electrode disposed-between saidcathode and said anode, said Cathodagrid and anode electrodes beingdisposed within saidenvelope, a first section of concentric.transmission line, a second section of concentric-transmission line,means 7 i securing the projectingedge of said metallic disk betweenabutting ends of the outer tubular conductors of the first and secondsections of concentric transmission line, a conductiveleadcon- Y nectedto said grid electrode and extending through the central aperture of.said cathode and through the glass envelope to'the central conduct'orofsaid first section ,oi transmission line, and a'conductive connectionbetween said anode velope, said central conductor of said second sectionof transmission line extending into said tube and being in directelectrical contact with said anode, a second grid electrode disposedbetween ,the first grid electrode and said anode, a metallic plateinside said envelope adjacent said metallic disk and separated from itby a layer of dielectric, and a conductive connection extending fromsaidsecond grid electrode to said metallic plate.

8. An electron discharge device according to claim 5, further comprisinga metal tube, wherein said anode is secured to said metal tube which issealed to a re-entrant portionof said glass envelope, said centralconductor of said second section of transmission line extending intosaid tube and being in direct electrical contact with said anode, asecond grid electrode and a third grid electrode disposed between thefirst grid electrode and said anode atcdifferent distances from saidcathode, and a direct conductive connection within said glass envelopeextending between said annular, metallic disk and the grid electrodenearest the anode. l

9, The combination according to claim 1', in combination with a metalring parallel to and spaced fromsaid disk, a dielectric layerintermediate said disk and ring, ,Wherebythe latter form a condenserbetween them, and means electrically interconnecting said screen grid,to said metalring.

, 10.Aneelectron discharge device comprising a glass envelope, ametallic disk extending across and sealed between two portions of saidenvelope, a cathode having, a plane electron emitting sur-, face,supported by said disk within said envelope, an anode havingra planesurface, means supporting said anode within said envelope with its planesurface parallel to and spaced from the plane surface of the cathode,first and second grid electrodes, means supporting said grid.elec-,-

trodes intermediate said cathode and anode, a

and the central conductor ofsaid second section I of transmission line.i a I 6. An electron discharge device according to claim 5, furthercomprising a metal tube, wherein said anode is secured to said metaltube which metallic ring in said envelope spaced from and parallel tosaid metallic disk, :a layer of dielectric material intermediate said"metallic ring and said metallic disk wherebys said ring and disk form acondenser within the envelope, and means electrically interconnectingsaid second grid with said metallic ring. 1

11. An electron discharge device comprising a glass envelope, a metallicdisk extending across.

and sealed between twoportions of said envelope, a cathode having aplane. electron emittingsurface, supported by said disk withinsaidenvelope, an anode having a plane surface, means supporting saidanode within said envelope with its plane surface parallel to and spacedfrom the plane surface of the cathode, three gridelectrodeslongitudinally spaced from one another and positionedintermediate said cathode and anode, and means within said envelopeelectrically interconnecting that grid electrodenearest the anode withsaid metallic disk.

. SVEN H. DODINGTON.

